Abstract: Source-to-site seismic motion simulation based on deterministic physics-based models constitutes a critical research frontier in earthquake engineering, while the expanding frequency bandwidth requirements impose dual challenges on both computational accuracy and efficiency of explicit time integration schemes in contemporary numerical simulations. This study develops a three-dimensional high-performance numerical scheme integrating fourth-order PEFRL (Position Extended Forest-Ruth Like) symplectic integration with spectral element method (SEM), designed to overcome the inherent limitations in accuracy, stability, and computational efficiency for broadband simulations within conventional SEM frameworks. The PEFRL algorithm innovatively refines the stepping protocol of con-ventional Forest-Ruth methods by reducing acceleration computations from quintuple to quadruple evaluations per timestep, complemented by a displacement-velocity staggered update paradigm that strategically optimizes memory allocation and computational expenditure. Benchmark evaluations against conventional second-order Newmark and fourth-order Runge-Kutta time integrators have been conducted across three distinct geological configurations: homogeneous, layered medium, and basin half-space models. Numerical validations reveal the enhanced PE-FRL-SEM's superior performance across four critical scenarios: half-space models demonstrate 16.7% phase error reduction and 20.6% energy error reduction, high-frequency source conditions achieve 55.4% and 36.3% im-provements, layered media show 20.7% and 22.3% enhancements, while basin models exhibit 21.3% and 24.7% error mitigation, accompanied by 33% computational acceleration relative to LDDRK benchmarks. Subsequently, the method was successfully applied to simulate three-dimensional broadband (0-10 Hz) ground motions for the 1994 Northridge MW6.7 earthquake. The simulation results exhibit excellent agreement with observations in terms of both amplitude and spectral characteristics. This methodology successfully reconciles the stability-efficiency paradox in broadband seismic field simulation, substantially advances the engineering applicability of strong ground motion prediction, and establishes a robust computational paradigm for regional seismic risk assessment and struc-ture-specific anti-seismic evaluations.